Inflammation

Question 1

what is inflammation/the inflammatory response?

Answer 1

the physiological response to tissue damage/injury and is accompanied by a characteristic series of local changes

Question 2

what is the purpose of inflammation?

Answer 2

to be protective

• isolate
• inactivate
• remove

both the causative agent and damaged tissue, so that healing can take place

Question 3

primary signs/symptoms of inflammation?

Answer 3

• redness
• heat
• swelling
• pain

Question 4

how are inflammatory conditions labelled/described?

Answer 4

by their latin suffix ‘itis’

• appendicitis; inflammation of the appendix
• laryngitis; inflammation of the larynx

Question 5

general cause of inflammation?

Answer 5

any form of tissue damage will stimulate the inflammatory response, even in the absence of infection

Question 6

does infection have to be present for inflammation to occur?

Answer 6

no, tissue damage alone can stimulate the inflammatory response

Question 7

examples of causes of inflammation?

Answer 7

• extremes of temperature
• trauma
• corrosive chemicals including extremes of pH
• abrasion
• infection by pathogen(s)

Question 8

what is acute inflammation?

Answer 8

• typically short in duration, e.g., days-weeks
• may range from mild to severe, depending on extent of tissue damage
• e.g., inflammatory response following cutting your hand

Question 9

what is chronic inflammation?

Answer 9

• slow, long-term inflammation lasting prolonged periods of time
• several months- years
• inflammation which ‘sticks around’ long after injury/infection
• processes involved are similair to those in acute inflammation, but as process is longer, more tissue damage is likely
• causes; untreated acute inflammation and autoimmune disorders (chronix exposure to an irritant), etc.

Question 10

difference between acute and chronic inflammation?

Answer 10

• acute; body’s response to sudden tissue damage
• chronic; body continues to send inflammatory cells despite no cause/need

Question 11

list of changes that occur during an inflammatory response

Answer 11

• increased blood flow
• accumulation of tissue fluid
• migration of leukocytes
• pain and suppuration (pus production)
• increased core temperature

These changes in the body will significantly overlap one another and develop together during an inflammatory response

Question 12

increased blood flow

Answer 12

• arterioles and local capillaries supplying damaged area dilate, increasing blood flow to the site of injury
• this is mainly caused by chemical mediators released from damaged cells, e.g., serotonin and histamine
• increased blood flow to the site of injury provides more O2 and nutrients
• increased blood flow causes the increased temperature and erythema of an inflamed area, and contributes to the swelling (oedema)

Question 13

increased tissue fluid formation

Answer 13

*common sign of inflammation is swelling of involved tissues, caused by fluid leaving local blood vessels and entering interstitial spaces

• this is partly due to increased capillary permeability caused by inflammatory mediators; serotonin, histamine, and prostoglandins
• also partly due to elevated pressure within vessels due to increased blood flow
• most excess tissue fluid drains away in the lymphatic vessels, taking damaged tissue, dead/dying cells, and toxins with it
• plasma proteins (normally retained within the blood) also escape into tissues through leaky capillary walls and this increases osmotic pressure, draining more fluid out of the blood

Question 14

how is increased tissue fluid/oedema harmful and helpful?

Answer 14

helpful; swelling around a painful, inflammed joint cushions it and limits movement, encouraging healing

harmful; swelling around respiratory passages can obstruct breathing, whilst significant swelling can cause pain

Question 15

increased temperature

Answer 15

• the increased temperature of inflamed tissues has twin beenfits of both inhibitng growth & division of microbes, whilst promoting activity of phagocytes
• inflammatory response may be accomadated by a rise in core body temperature (pyrexia/fever) especially if bacteria infection is present
• pyrexia increases the metabolic rate of cells in the inflamed area, causing an increased need for O2 and nutrients

Question 16

pain

Answer 16

• occurs when local swelling compresses sensory nerve endings
• pain is exacerbated by chemical mediators of the inflammatory process, e.g., bradykinin and postaglandins which increase the sensitivity of sensory nerve endings to painful stimuli
• although unpleasant, pain may indirectly promote healing as it encourages protection of the damaged site

Question 17

suppuration (pus formation)

Answer 17

• pus consists of dead phagocytes, dead cells, fibrin, inflammatory exudate and living/dead microbes
• a localised collection of pus within the tissues is called an abscess

Question 18

outcomes of acute inflammation

Answer 18

resolution; occurs when the cause has been successfully overcome. new, healthy tissue is formed in replacement, repair is complete, with or without scar formation

development of chronic inflammation; can occur if resolution is not complete, e.g., if live microbes remain at site of injury, in deep seated abscesses, wound infections, bone infections

Question 19

migration of leukocytes

Answer 19

• loss of fluid from the blood thickens it, slowing blood flow and allowing normally fast-flowing WBCs to make contact & ahdere to the damaged vessel wall
• on acute inflammation, the most important luekocyte is the neutrophil conducts phagoctyosis of antigens once within the tissues
• phagocyte activity is promoted by the increased temperature (local & systemic) associated with inflammation
• after 24hrs, macrophages become most dominant WBC at inflammed site, and persist if situation is not resolved, resulting in chronic inflammation
• chemotaxis; the chemical attraction of leukocytes, including neutrophils and macrophages, to an area of inflammation

Question 20

what are inflammatory mediators?

Answer 20

substances which act on blood vessels and/or cells to promote an inflammatory response. they are released by tissues, blood, and primarily relevant cells, e.g., types of WBCs

Question 21

types of inflammatory mediators

Answer 21

• histamine
• serototonin
• prostaglandins
• heparin
• bradykinin

Question 22

histamine

Answer 22

made by; mast cells (tissues) & basophils (blood)

trigger for release; binding of an antibody to mast cells and basophils

main pro-inflammatory actions; vasodilation, increased vascular pearmeability, degranultion, smooth muscle contraction (such as bronchocinstriction)

Question 23

serotonin

Answer 23

made by; platelets (tissues), basophils (blood)

tirgger for release; when platelets are activated and when mast cells/basophils degranulate

main pro-inflammatory actions; vasoconstriction, increased vascualr permeability

Question 24

prostaglandins

Answer 24

made by; nearly all cells, not stored but made from cell membranes as requiered

trigger for release; various stimuli, e.g., drugs, toxins, other inflammatory mediators, hormones, trauma, etc.

main pro-inflammatory actions; diverse, sometimes opposing e.g., pyrexia, pain, vasodilation or vasoconstriction, increased vascular permeability

Question 25

heparin

Answer 25

made by; liver, mast cells, basophils

trigger for release; when cells degranulate

main pro-inflammatory actions; anticoagulant (prevents blood clotting), which also maintains blood supply (nutrients & O2) to injured tissue and washes away microbes and wastes

Question 26

bradykinin

Answer 26

made by; tissues & blood

trigger for release; when blood clots, in trauma and inflammation

main pro-inflammatory actions; pain & vasodilation